“IQ Constancy and Age”, 1972-10-01 ():
The WISC was given to 173 normal children, ages 5 to 13 years, on 3 consecutive occasions at yearly intervals.
Only the Full-scale IQ data were presented in this paper. Of the 18 between-year comparisons of mean Full-scale IQ, only 1 was significantly higher. Of the 9 between 2-year comparisons, only 2 were significantly higher.
Correlation analysis showed a perfect relationship between magnitude of correlations and lapsed time as well as a distinctive trend regarding the increase of magnitude of correlation with increasing age.
No sex differences in the patterning of IQ changes were noted (only 1 of the 54 comparisons was significant). There was no consistent pattern of change in IQ scores of the low-IQ subgroup compared with the high-IQ subgroup.
Three factors are discussed as being important in longitudinal studies, namely, maturation, sex, and individual differences in IQs of subjects.
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